Does A Chocolate Habit Help Keep You Lean?

A new study finds that people who eat chocolate several times a week are actually leaner than people who don't eat chocolate regularly.

Really, we asked? Last time we checked chocolate was loaded with fat and sugar. But this new research, along with some prior studies, suggests chocolate may favorably influence metabolism.

To test this theory, Beatrice Golomb, an associate professor of medicine at the University of California, San Diego, asked about 1,000 people, ages 20 to 85, a simple question: "How many times a week do you consume chocolate?" The participants then completed food frequency questionnaires to estimate their caloric intakes of a whole range of foods including chocolate. They also had weight and height measurement taken to calculate their body mass index, or BMI.

"In our study, people who ate chocolate more often actually ate more calories," says Golomb. "But in spite of that they had lower [BMI]."

How much lower? For a 5-foot-tall woman, weighing about 120 pounds, the study found that she was likely to be about 5 pounds lighter if she was a frequent eater of chocolate (five times a week).

And, no, the people with serious chocolate habits did not exercise more than those who weren't in the habit of eating chocolate.

"So exercise was not an explanation for the finding," says Golomb.

This study certainly does not prove that frequent chocolate consumption causes people to be leaner: The researchers found that chocolate's correlation to thinness started to melt away among the participants who consumed the most. They also didn't suss out whether the type of chocolate — white, milk, or dark, which can have varying amounts of cocoa — made a difference.

But what's fascinating here is the notion that our bodies may not treat all calories the same way.

"I think a really important point is that it isn't just the number of calories that matter," says Golomb. But the composition of calories seems to matter, too.

Not all researchers are convinced of this. Broadly speaking, the "calories in, calories out" method of managing weight is effective for most people.

And it's possible that overweight participants in the study under-reported their their chocolate consumption, according to Jane Wardle of the University College London. Indeed, a lot of researchers agree that self-reported food data can be flawed. (Editor's note: This was added Tuesday 12:20 p.m. ET.)

But what research shows is that certain foods contain compounds that have some power to positively influence metabolic factors.

"When people talk about the health benefits of chocolate," says food scientist Joshua Lambert of Penn State University, "they typically talk about compounds called polyphenols."

When he investigated some specific polyphenols found in cocoa, he found that they potently inhibit an enzyme, called pancreatic lipase, that's responsible for digesting dietary fat.

This means that the fat in chocolate may exit our bodies before it has a chance to be absorbed. Or, in other words, these compounds in cocoa may help us fend off fat.

Lambert's studies have been conducted in test tubes and mice, not in people. "So there's a big leap from what we're doing to what the [UC San Diego researchers] are doing."

But it might be one mechanism that explains why frequent chocolate eaters tend to be leaner.

Another possible mechanism is that the compounds in chocolate may increase the energy that cells make. Researchers are studying this as well.

So, for now, if you're a chocolate lover, lose the guilt. Or, be reassured, for now, that the associations between eating chocolate and body weight move in the preferred direction.

And one more thing: This study was not funded by the chocolate industry. Funding came from the National Institute of Health; the National Heart, Lung, and Blood Institute; and the UC San Diego General Clinical Research Center.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

ROBERT SIEGEL, HOST:

From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.

MELISSA BLOCK, HOST:

And I'm Melissa Block. Here's one from the run-that-by-me-again department. Chocolate may help make you thinner. See what I mean? NPR's Allison Aubrey has details on a new study. It suggests those of us with a chocolate habit could be doing our body weight a favor.

ALLISON AUBREY, BYLINE: Physician Beatrice Golomb says prior research has hinted that chocolate may favorably influence metabolism and she was curious to find out whether this would be reflected in chocolate lovers' body weights.

BEATRICE GOLOMB: Well, you know, I actually had the hubris to think that the metabolic effect might be such that modest amounts of chocolate eaten regularly could be body mass index neutral.

AUBREY: Meaning, perhaps all or some of those calories could be offset by the way our bodies handle chocolate. To test this theory, Golomb and her colleagues asked about 1,000 men and women aged 20 to 85 years old to complete a food frequency questionnaire, or FFQ.

GOLOMB: The FFQ asks in depth questions about regular foods that people have eaten recently and calculate things like calories consumed.

AUBREY: From people's answers, they determined how much chocolate people consumed and how often and then she and her colleagues recorded each person's BMI, or body mass index. And what did they find?

GOLOMB: In our study, people who ate chocolate more often actually ate more calories, but in spite of that, they had lower body mass index.

AUBREY: How much lower? Golomb says, if you take a five foot tall woman who weighs 120 pounds, this study found that, if she was a regular chocolate eater, she was likely to be about five pounds lighter compared to someone who didn't eat much chocolate. And it's not because she was out running marathons.

GOLOMB: In fact, people who ate chocolate more often did not exercise any more, so exercise was not an explanation for the finding.

AUBREY: Now, none of this proves that chocolate can help people maintain healthy weights and the researchers didn't suss out whether the type of chocolate made a difference, but they did find that the correlation to thinness started to melt away among the people who had the highest consumption. And this suggests that there is a point at which the metabolic benefits don't cancel out the extra calories.

Even so, Golomb says her findings still support the idea that the body doesn't treat all calories the same way.

GOLOMB: I think a really important point is that it isn't just the number of calories that matters, but the composition of calories.

AUBREY: Not all researchers are convinced of this. Broadly speaking, the calories in, calories out method of managing weight is effective for most people. But what research is showing is that certain foods contain compounds that have some power to influence metabolic factors in a favorable way and chocolate is one of them, explains food scientist Joshua Lambert of Penn State.

JOSHUA LAMBERT: When people talk about the health beneficial effects of chocolate, they talk about these compounds called polyphenols.

AUBREY: Now, polyphenols may have a range of beneficial biological effects, but Lambert says he focused in on one possible mechanism that could help explain the new study.

LAMBERT: When we started looking in our lab at some of these compounds in cocoa, these polyphenolic compounds, we actually found that they very potently inhibited the enzyme that's responsible for digesting dietary fats.

AUBREY: This means that the fat that comes with chocolate may exit our bodies before it has a chance to be absorbed. In other words, these compounds in cocoa could help us fend off fat?

LAMBERT: Right. You don't absorb the fat.

AUBREY: Now, Lambert says the caution here is that his lab work has been done in test tubes and mice, not people, like the U.C. San Diego study.

LAMBERT: There's a big leap from what we're doing to what they're doing.

AUBREY: But it could be one explanation that explains why frequent chocolate eaters tend to be leaner. Whatever the explanation, Beatrice Golomb says this is the thought she'd leave chocolate lovers with.

GOLOMB: Maybe those of us who do eat chocolate a few times a week can feel less guilt.

AUBREY: And be reassured for now that a little chocolate may, in fact, be good for your waistline. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.